1. Field of the Invention
The present invention relates to a zoom lens and an image pickup device, and particularly to a technical field of a miniaturized higher-performance zoom lens suitable for a photographing optical system of digital input-output devices such as a digital still camera, a digital video camera and the like and an image pickup device using the zoom lens.
2. Description of the Related Art
Image pickup devices using a solid-state image pickup element such as a digital still camera and the like have recently been spread. With the spread of such image pickup devices such as a digital still camera and the like, even higher image quality is desired. In a digital still camera or the like having a large number of pixels, in particular, there is a desire for a photographing lens, especially a zoom lens, that has excellent image forming performance and which lens is compatible with a solid-state image pickup element having the large number of pixels.
There is also an increasing desire for a wider angle of view as well as higher image quality as described above, and there is a desire for a small zoom lens having a high variable power ratio and a wide angle of view such for example as a half angle of view of more than 40°.
There are many kinds of zoom lenses for digital still cameras. However, as a lens type suitable for achieving a reduced size and a wider angle of view, a three-group zoom lens is known which zoom lens is formed by arranging a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power in order from an object side to an image side (see for example Japanese Patent Laid-Open Nos. 2004-13169, 2006-113554, 2007-212636 and 2007-140359, hereinafter referred to as Patent Documents 1 to 4, respectively).
In the zoom lenses described in Patent Document 1 and Patent Document 2, a wider angle of view is achieved by forming the first lens group by three lenses.
In the zoom lenses described in Patent Document 3 and Patent Document 4, miniaturization is achieved by forming the first lens group by two lenses. In the zoom lens described in Patent Document 4, in particular, miniaturization is achieved by forming the first lens group by two lenses and further actively bringing about distortion aberration.